1. Field of the Invention
This invention relates to a catheter having a balloon at its distalmost end, and having means for adjustably controlling the stiffness of the catheter shaft, and more particularly to a convertible-type balloon catheter having stiffener means disposed within the catheter.
2. Prior Art
Balloon catheters are utilized for insertion into the human body into lumens therewithin. The catheters are of necessity made of a flexible plastic extrusion such as polyethelene, polyester or polyamide. Advancement and manipulation of a catheter requires a certain stiffness or pushability of the catheter itself, by the physician, without injuring the patient in which the catheter is placed.
A number of approaches have been made, in attempting to provide stiffness to catheters. U.S. Pat. No. 4,964,853 to Sugiyama et al shows a balloon catheter having a braided wire member disposed within the catheter body itself in a mesh-like manner. Mesh is imbedded in the wall of the inner tube. U.S. Pat. No. 4,875,841 to Higgins shows a balloon catheter having a coiled wire arranged within the proximalmost hub, which coiled wire extends in an uncoiled manner within the body of the catheter shaft itself. The coil and the wire itself being co-rotatable so as to provide rotational stiffness to the catheter.
U.S. Pat. No. 4,822,345 to Danforth shows a variable stiffener balloon catheter, for percutaneous transluminal coronary angioplasty procedures. This patent to Danforth shows a method of providing for variable flexibility, by the use of a longitudinally extended balloon arranged along the exterior of the catheter shaft. Pressurization or depressurization of this balloon is effectuated by a syringe, which pressurizably controls the rigidity of the balloon itself. A further embodiment of this concept of Danforth utilizes relatively stiff wires running through channels in the periphery of the catheter, the wires adding the stiffness to the catheter.
The preformed catheter assembly shown in U.S. Pat. No. 4,738,667 to Galloway discloses a sheath which is slideably mounted over the catheter so as to be moved from the proximal to the distal end, to straighten out the distal end during insertion and removal of the catheter from a body. The catheter assembly shown in U.S. Pat. No. 4,737,152 to Alchas shows a stylet or stiffening wire arranged within a lumen connected to the closed distal end of the catheter and also there is a loop on its proximalmost end. The loop is arranged in a rotatable knob to facilitate rotation of the distal end of the catheter while providing stiffness, while the proximal end is turned.
U.S. Pat. No. 4,586,923 issued to Gould et al shows a curving tip catheter having a catheter body which includes a sheath of braided wire having a meshlike configuration positioned around the wall of the tubular body to provide tortional stiffness to the body relative to the flexible tip. In an alternative embodiment, a relatively stiff but bendable inner plastic tubing can be inserted within the tubular body to provide tortional stiffness to that body. In a somewhat similar vein, U.S. Pat. No. 4,516,972 to Sampson shows a guiding catheter having a helically wound ribbon of flexible material embedded within the wall of the catheter, so as to provide tortional rigidity and stiffness.
In yet a further embellishment on the idea of stiffening a balloon catheter, U.S. Pat. No. 4,448,195 to LeVeen et al shows a reinforced balloon catheter which has a guidewire adapted to be inserted for stretching the catheter when it is inserted into a blood vessel to stiffen the catheter and position it. In an alternative arrangement, a braided shell wire reinforcement is used within the braids, which are placed at the beginning and endings of the thinned portion of the catheter. U.S. Pat. No. 4,033,331 to Guss et al, discloses a contour or stiffening wire slideably disposed within a lumen extending substantially the full length of the catheter. Slight retraction of the stiffening wire from the distal end of the lumen permits catheter to assume a predetermined curvature thereat.
It is thus an object of the present invention to provide a catheter having variable stiffness capabilities therewithin. The catheter of the present invention should overcome the problems of the prior art by getting the physician to properly adjust the rigidity or stiffness of the catheter shaft according to the particular situation that warrants it in conjunction with the capability of utilizing the catheter shaft in a convertible manner between a xe2x80x9crapid-exchangexe2x80x9d mode and an xe2x80x9cover-the-wirexe2x80x9d mode.
The present invention comprises a balloon catheter having a catheter shaft with at least three lumens extending from the proximal to the distal ends thereof. The first and second lumens may preferably but not necessarily be of cresent shape in cross-section, and the third lumen is of circular cross-section. At least one of the cresent shaped lumens has a stiffening mandrel extending therethrough. In a preferred embodiment, the third lumen has a side opening arranged relatively close yet proximal to the balloon at the distal end of the catheter assembly.
The balloon on the distal end of the catheter shaft is in fluid communication with one of the cresent shaped lumens. The first shaped lumen has a closed distalmost end, at the proximal end of the balloon.
The third lumen, preferably of circular cross-section, extends from the proximal end of the catheter shaft, and through the balloon, open at its distalmost end at the distal end of the balloon. The third lumen is adapted to receive a guidewire, either through the entire length thereof, or from an opening proximal of the balloon and through to its distalmost end.
In a preferred embodiment, a guidewire is adaptable to enter the third xe2x80x9cdistalxe2x80x9d lumen at its opening at the distalmost end of the catheter and extend through that lumen, through the balloon, and exit out the side opening through the sidewall of the catheter, proximal of the balloon. The side xe2x80x9cguidewirexe2x80x9d opening of the third lumen being disposed through the wall of the catheter shaft at a location which is also proximal to the distal end of the stiffening mandrel in the first cresent shaped lumen. This rapid exchange mode with a guidewire extending partway through may occur with a stiffening stylet disposed within the third lumen, the stylet extending up to a location adjacent the side opening, from the proximal end of the catheter. This same lumen, a portion of which is utilized for the xe2x80x9crapid-exchangexe2x80x9d mode, is utilized in its entire length, for the catheter in its xe2x80x9cover-the""wirexe2x80x9d mode, where a guidewire enters the distal opening of the third xe2x80x9cdistalxe2x80x9d lumen, and exits at the proximal end of the catheter at the proximal end of that third lumen, through a connector or adaptor.
The present invention thus comprises a multiple lumen catheter (at least three lumens) having proximal and distal ends, the proximal end having a Y-connector thereat for adaptation of inflation devices or control functions, the distal end comprising an inflatable elongated balloon.
A first of the lumens has an elongated stiffening mandrel disposed therein, the lumen being closed at its distalmost end. The stiffening mandrel being preferably made of Nitinol. A second of the lumens extending from the connector, and into the balloon, providing fluid communication therewith. The third of the lumens being preferably circular in cross-section, extending from the connector and through the balloon, and open through the distal tip of the catheter shaft. A xe2x80x9csidexe2x80x9d orifice being disposed through the wall of the catheter and into the third lumen, just proximal (about 15 to 35 cm) of the balloon. The stiffening mandrel in the first lumen extending distally of the side orifice in the third lumen to the proximal end of the catheter, so as to allow a smoother transition of catheter stiffness when the assembly is utilized in a rapid exchange modexe2x80x94that is, when a guidewire extends only part way through the third lumen, out through the xe2x80x9csidexe2x80x9d orifice after entering that lumen distally and to help transmit xe2x80x9cpushxe2x80x9d on the catheter shaft from""its proximal end. The same lumen therefore, in the same catheter, functioning as a lumen for an xe2x80x9cover-the-wirexe2x80x9d mode, as well as a xe2x80x9crapid-exchange-wirexe2x80x9d mode, using part of the lumen for a guidewire and part of that lumen for catheter stiffening assistance.